1. Field of the Invention
The present invention relates to a coating solution for a non-light-emitting organic semiconductor device, an organic transistor, a compound, an organic semiconductor material for a non-light-emitting organic semiconductor device, a material for an organic transistor, a method for manufacturing an organic transistor, and a method for manufacturing an organic semiconductor film. Specifically, the present invention relates to a compound having a thieno[3,2f:4,5-f′]bis[1]benzothiophene skeletal structure and to a coating solution for a non-light-emitting organic semiconductor device, an organic transistor, an organic semiconductor material for a non-light-emitting organic semiconductor device, a material for an organic transistor, a method for manufacturing an organic transistor, and a method for manufacturing an organic semiconductor film which use a compound having a thieno[3,2-f:4,5-f′]bis[1] benzothiophene skeletal structure.
2. Description of the Related Art
Devices using organic semiconductor materials are drawing great attention because they are expected to be superior in various aspects to devices using inorganic semiconductor materials of the related art such as silicon. Examples of the devices using organic semiconductor materials include a photoelectric conversion element such as an organic thin-film solar cell or a solid-state imaging element using organic semiconductor materials as photoelectric conversion materials, an organic transistor (referred to as an organic thin-film transistor in some cases) having non-light-emitting properties (in the present specification, “non-light-emitting” refers to properties by which a luminous efficiency of equal to or less than 1 lm/W is obtained in a case where electric currents are applied to a device at a current density of 0.1 mW/cm2 at room temperature in the atmosphere; non-light-emitting organic semiconductor devices mean organic semiconductor devices excluding light-emitting organic semiconductor devices such as organic electroluminescence elements), and the like. Compared to the devices using inorganic semiconductor materials, the devices using organic semiconductor materials are likely to make it possible to prepare large area elements at lower temperature and lower costs. Furthermore, the characteristics of the materials can be easily changed by varying the molecular structure thereof. Therefore, the materials show a wide variation and can realize functions or elements that cannot be obtained by inorganic semiconductor materials.
Regarding organic transistor materials, the use of compounds having a fused ring in a semiconductor active layer is examined so as to improve carrier mobility and to improve transistor performances.
As materials for an organic transistor, compounds having a thieno[3,2-f:4,5-f′]bis[1]benzothiophene (hereinafter, referred to as TBBT as well) structure on the inside thereof are known. For example, Tetrahedron 66 (2010) 8778-8784 discloses a method for synthesizing a compound C6-TBBT or C12-TBBT obtained by substituting thieno[3,2-f:4,5-f′]bis[1]benzothiophene with an alkyl group having 6 carbon atoms or an alkyl group having 12 carbon atoms respectively, and discloses absorption/emission spectra and cyclic voltammetry (CV) as physical properties of the compound. Tetrahedron 66 (2010) 8778-8784 describes the application of the compound to an organic transistor in the introduction part of the document. However, the document merely describes the measurement of the absorption/emission spectra or the oxidation-reduction potential of the solution, but does not describe the formation of a film, the physical properties of the film, the evaluation of organic transistor characteristics such as carrier mobility, and the like.